Frontend & browser·Modules, bundling and the build
you saved the file and the component updated on screen without losing what you had typed into the form.
Hot module replacement
Also calledHMR, hot reload, fast refresh
Swapping a changed module into the running application without a full reload, preserving state where it can. It is the main reason dev servers exist as separate machinery from the production build. It is also a source of confusing behaviour: state that survives a hot update can hide a bug that a real load would expose, so anything odd deserves a hard refresh before it is investigated.